Medical College of Wisconsin
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The yeast F(1)F(0)-ATP synthase: analysis of the molecular organization of subunit g and the importance of a conserved GXXXG motif. J Biol Chem 2005 Jul 01;280(26):24435-42

Date

05/12/2005

Pubmed ID

15886192

DOI

10.1074/jbc.M502804200

Abstract

The F(1)F(0)-ATP synthase enzyme is located in the inner mitochondrial membrane, where it forms dimeric complexes. Dimerization of the ATP synthase involves the physical association of the neighboring membrane-embedded F(0)-sectors. In yeast, the F(0)-sector subunits g and e (Su g and Su e, respectively) play a key role in supporting the formation of ATP synthase dimers. In this study we have focused on Su g to gain a better understanding of the function and the molecular organization of this subunit within the ATP synthase complex. Su g proteins contain a GXXXG motif (G is glycine, and X is any amino acid) in their single transmembrane segment. GXXXG can be a dimerization motif that supports helix-helix interactions between neighboring transmembrane segments. We demonstrate here that the GXXXG motif is important for the function and in particular for the stability of Su g within the ATP synthase. Using site-directed mutagenesis and cross-linking approaches, we demonstrate that Su g and Su e interact, and our findings emphasize the importance of the membrane anchor regions of these proteins for their interaction. Su e also contains a conserved GXXXG motif in its membrane anchor. However, data presented here would suggest that an intact GXXXG motif in Su g is not essential for the Su g-Su e interaction. We suggest that the GXXXG motif may not be the sole basis for a Su g-Su e interaction, and possibly these dimerization motifs may enable both Su g and Su e to interact with another mitochondrial protein.

Author List

Saddar S, Stuart RA

Author

Rosemary Stuart PhD Professor in the Biology department at Marquette University




MESH terms used to index this publication - Major topics in bold

Amino Acid Motifs
Amino Acid Sequence
Blotting, Western
Cloning, Molecular
Cross-Linking Reagents
Cysteine
Dimerization
Glycine
Mitochondrial Proton-Translocating ATPases
Molecular Sequence Data
Mutagenesis, Site-Directed
Mutation
Phenotype
Protein Structure, Tertiary
Saccharomyces cerevisiae
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a